Anti-ulcer 5-(2-substituted ethenyl)-3(2H)-furanones

ABSTRACT

A compound of the formula: ##STR1## in which R is alkyl, phenyl or halophenyl; R 2  is substituted phenyl having from 1 to 3 substituents selected from halo, alkyl, alkylthio, alkylsulfonyl, cyano, trifluoromethyl, or R 2  is pyridinyl, pyrazinyl, quinolinyl, N-alkylpyrrolyl, thienyl, benzothienyl, or furyl; and n is 1 or 2, are cytoprotective anti-ulcer agents.

This is a division of application Ser. No. 07/449,620, now U.S. Pat. No.4,966,905, filed Dec. 12, 1989.

DESCRIPTION OF THE INVENTION

In accordance with this invention, there is provided a group of novel5-ethenyl-3(2H)-furanone derivatives, pharmaceutical compositionscontaining those novel compounds and a process for treating and/orpreventing ulcers by administering certain 5-ethenyl-3(2H)-furanonederivatives to mammals in need of such cytoprotective-antiulcertreatment.

The novel compounds of this invention present the following structuralformula: ##STR2## in which R¹ is alkyl of 1 to 6 carbon atoms, phenyl orhalophenyl;

R² is substituted phenyl having from 1 to 3 substituents selected fromhalo, alkyl of 1 to 6 carbon atoms, alkylthio of 1 to 6 carbon atoms,alkylsulfonyl of 1 to 6 carbon atoms, cyano, trifluoromethyl, or R² ispyridinyl, pyrazinyl, quinolinyl, N-alkylpyrrolyl in which the alkylsubstituent has 1 to 6 carbon atoms, thienyl, benzothienyl, or furyl;and

n is 1 or 2.

Within that group of compounds, there resides a preferred subgenus ofcompounds based upon their profile of activity. This subgroup ofcompounds are of the formula: ##STR3## in which R¹ is methyl, phenyl or4-fluorophenyl; and

R² is bromo-, chloro-, fluoro-, dichloro, difluoro or cyano-substitutedphenyl or R² is thienyl, pyridinyl, pyrazinyl or quinolinyl.

The pharmaceutical composition and method of use aspects of thisinvention involve both the novel compounds of the genus disclosed,supra, as well as the known compound2,2-dimethyl-5-(2-phenylethenyl)-3(2H)-furanone (Chem. Lett., pp.323-326, 1987, Chem. Soc. J.). The pharmaceutical compositions are bestdescribed as:

A compound of the formula: ##STR4## in which R¹ is alkyl of 1 to 6carbon atoms, phenyl or halophenyl;

R² is phenyl or substituted phenyl having from 1 to 3 substituentsselected from halo, alkyl of 1 to 6 carbon atoms, alkylthio of 1 to 6carbon atoms, alkylsulfonyl of 1 to 6 carbon atoms, cyano,trifluoromethyl, or R² is pyridinyl, pyrazinyl, quinolinyl,N-alkylpyrrolyl in which the alkyl substituent has 1 to 6 carbon atoms,thienyl, benzothienyl, or furyl; and

n is 1 or 2;

and a pharmaceutically acceptable carrier therefor.

The preferred pharmaceutical compositions involve the preferredcompounds in conjunction with a pharmaceutically acceptable carrier.

The novel compounds of this invention are prepared by reaction of theappropriately substituted 2,5-dimethyl-3(2H)-furanone with anappropriately substituted aldehyde, thusly: ##STR5## The products areproduced in the trans (E)-isomeric form about the vinylene group(s).

The intermediate furanone derivatives are obtained by the followingtechniques.

The 2,2,5-trimethyl-3(2H)-furanone starting material is a known compound[J.A.C.S. 103 1501 (1981)]. It is readily prepared by hydrogenation of3-methyl-5-(1-hydroxy-1-methylethyl)isoxazole, which in turn isobtainable by the addition of nitroethane to 2-methyl-3-butyn-2-ol inthe presence of phosphorus oxychloride. The following detailed procedureillustrates the method used.

To a solution of 2-methyl-3-butyn-2-ol (675 mL, 6.97M), triethylamine(1500 mL, 10.76M), and nitroethane (350 mL, 4.0M) in chloroform (4 L) at10° C. was added a solution of phosphorus oxychloride (438 mL, 4.72M) inchloroform (1.5 L) dropwise over eight hours. After the addition, thereaction solution was warmed to room temperature and was stirredovernight. The reaction solution was then washed with water (2×2 L),saturated aqueous sodium bicarbonate (2×2 L), dried over sodium sulfateand filtered. After the solvent was removed under reduced pressure, thedark residual oil was distilled (85° C., 1 mm) to give a dark orangeliquid (343 g, 49.7%) ¹ H NMR (CDCl₃, 100 MHz): δ 6.05 (s, 1H), 3.08(brs, 1H), 2.16 (s, 3H), 1.54 (s, 6H).

To a solution of 10% palladium on charcoal (50 g) in MeOH (800 mL) undernitrogen was added a solution of3-methyl-5-(1-hydroxy-1-methylethyl)-isoxazole (109 g, 0.77M) in MeOH(200 mL). The reaction mixture was hydrogenated at 30 psi in a Parrhydrogenation apparatus till there was no more hydrogen uptake. Thecatalyst was removed by filtration under nitrogen and washed with MeOH(2×100 mL). The resulting filtrate was concentrated under reducedpressure to yield a white crystalline solid (106.2 g).

This product was suspended in water (200 mL) and 1N hydrochloric acid(400 mL) and stirred for 2 hours. The reaction mixture was thenneutralized with solid sodium bicarbonate and saturated with sodiumchloride. The aqueous solution was extracted with diethyl ether (5×100mL). The combined ethereal extracts were dried over magnesium sulfate,filtered and concentrated under reduced pressure to give a yellow liquid(82.7 g, 85% from the isoxazole). This procedure was repeated and thecombined crude products were distilled (bp=100°-102° C. at 1 mm) toyield 2,2,5-trimethyl-3(2H)-furanone as a clear liquid (140 g, 72%). ¹ HNMR (CDCl₃, 100 MHz): δ 5.36 (s, 1H), 2.21 (s, 3H), 1.40 (s, 6H).

The 2,5-dimethyl-2-phenyl-3(2H)-furanone reactant is prepared asfollows:

To a solution of acetaldoxime (44.5 g, 0.75M), 3-butyn-2-ol (52.9 g,0.75M) and triethylamine (10.5 mL, 0.075M), in dichloromethane (1.75 L)at 0° C., was added a 5% aqueous solution of sodium hypochlorite(bleach, 1.94 kg) over three hours. The reaction mixture was warmed toroom temperature and allowed to stir overnight.

The layers were separated and the aqueous layer was extracted withdichloromethane 5×100 mL). The combined dichloromethane extracts werewashed with saturated aqueous sodium chloride (500 mL), dried overMgSO₄, filtered and concentrated under reduced pressure to give3-methyl-5-(1-hydroxyethyl)-isoxazole as a yellow oil (47.7 g, 50%) thatwas used without further purification. ¹ H NMR (CDCl₃, 100 MHz): δ 6.25(s, 1H), 4.95 (q, J=5 Hz, 1H), 2.25 (s, 3H), 1.53 (d, J=5 Hz, 3H).

To a solution of 3-methyl-5-(1-hydroxyethyl)-isoxazole (47.6 g, 367 mM)in acetone (2 L) at 0° C., was added a solution of chromic anhydride(93.3 g, 933 mM), 6N aqueous sulfuric acid (186.15 mL, 1.1M) and water(186 mL) over two hours. After the reaction solution was allowed to warmto room temperature, saturated aqueous sodium chloride was added. Theaqueous layer was extracted with dichloromethane (3×400 mL). Thecombined organic extracts were washed with saturated aqueous sodiumsulfite (2×300 mL) and saturated aqueous sodium chloride (2×300 mL). Theorganic layer was dried over MgSO₄, filtered and concentrated underreduced pressure to give 3-methyl-5-acetoxy-isoxazole as a yellow powder(27.8 g, 60%) that was used without further purification. ¹ H NMR(CDCl₃, 100 MHz): δ 7.55 (s, 1H), 2.65 (s, 3H), 2.43 (s, 3H).

To a solution of 3-methyl-5-acetoxy-isoxazole (14 g, 112 mM) in diethylether (400 mL) at 0° C., was added a 3M solution of phenylmagnesiumbromide in diethyl ether (44.7 mL, 134 mM) dropwise. After the additionwas complete, the reaction mixture was stirred for 30 minutes. When pH 7buffer (100 mL) was added, the layers were separated. The aqueous layerwas extracted with diethyl ether (2×75 mL). The combined etherealextracts were washed with saturated aqueous sodium chloride (50 mL),dried over MgSO₄, filtered and concentrated under reduced pressure togive 3-methyl-5-(1-hydroxy-1-phenylethyl)-isoxazole as an amber oil(20.2 g, 89%) that was used without further purification. ¹ H NMR(CDCl₃, 100 MHz): δ 7.40 (m, 5H), 6.0 (s, 1H), 2.38 (s, 3H), 1.87 (s,3H).

The catalyst (10% Pd/C, 20 g) was suspended in methanol (800 mL) and asolution of 3-methyl-5-(1-hydroxy-1-phenylethyl)-isoxazole (20.2 g, 99.4mM) in methanol (200 mL) was added. The reaction mixture washydrogenated under 20 psi until there was no more uptake of hydrogen.After the reaction mixture was degassed, the catalyst was removed byfiltration and the filtrate was concentrated under reduced pressure.

The above crude product was dissolved in 1N aqueous hydrochloric acid(100 mL) and methanol (100 mL) and stirred one hour. Then the reactionsolution was neutralized with solid sodium bicarbonate and diluted withsaturated aqueous sodium chloride (200 mL). The aqueous solution wasextracted with diethyl ether (4×100 mL). The combined ethereal extractswere dried over MgSO₄, and concentrated under reduced pressure to afford2,5-dimethyl-2-phenyl -3(2H)-furanone as a yellow oil (12.5 g, 67%) thatwas used without further purfication. ¹ H NMR (CDCl₃, 100 MHz): δ 7.42(m, 5H), 5.42 (s, 1H), 2.32 (s, 3H), 1.73 (s, 3H).

The intermediate 2,5-dimethyl-2-(4-fluorophenyl) -3(2H)-furanone isproduced in the same manner as the 2-phenyl analogue, supra. Thus, to asolution of 3-methyl-5-acetoxy-isoxazole (0.5 g, 4 mM) in diethyl ether(25 mL) at 0° C., was added a 2N ethereal solution of phenylmagnesiumbromide in diethyl ether (2.4 mL, 4.8 mM), dropwise. After the additionwas complete, the reaction mixture was stirred 30 minutes. When pH 7buffer (10 mL) was added, the layers were separated. The aqueous layerwas extracted with diethyl ether (2×25 mL). The combined etherealextracts were washed with saturated aqueous sodium chloride (10 mL),dried over MgSO₄, filtered and concentrated under reduced pressure togive 3-methyl-5-[1-hydroxyl-1-(4-fluorophenyl)ethyl]-isoxazole as anamber oil (0.8 g, 91%) that was used without further purification. ¹ HNMR (CDCl₃, 100 MHz): δ 7.4 (dd, J.sub. 1 =6 Hz, J₂ =2.5 Hz, 2H), 7.0(t, J=5 Hz, 2H), 5.95 (s, 3H), 2.25 (s, 3H), 1.88 (s,3H).

The catalyst (10% Pd/C, 15 g) was suspended in methanol (400 mL), and asolution of 3-methyl-5-[1-hydroxy-1-(4-fluorophenyl)ethyl]isoxazole (15g, 73.8 mM) in methanol (100 mL) was added. The reaction mixture washydrogenated under 20 psi until there was no more uptake of hydrogen.After the reaction mixture was degassed, the catalyst was filtered andthe filtrate was concentrated under reduced pressure.

The above crude product was dissolved in 1N aqueous hydrochloric acid(100 mL) and methanol (100 mL) and stirred for one hour. Then thereaction solution was neutralized with solid sodium bicarbonate anddiluted with saturated aqueous sodium chloride (100 mL). The aqueoussolution was extracted with diethyl ether (4×100 mL). The combinedethereal extracts were dried over MgSO₄, filtered and concentrated underreduced pressure to afford2-methyl-2-(4-fluorophenyl)-5-methyl-3(2H)-furanone as a yellow oil(10.7 g, 67%) that was used without further purification. ¹ H NMR(CDCl₃, 100 MHz): δ 7.49 (dd, J₁ =6 Hz, J₂ =2.5 Hz, 2H), 7.02 (t, J=8Hz), 5.42 (s, 1H), 2.35 (s, 3H), 1.72 (s, 3H).

The following examples illustrate the preparation of the novel compoundsof this invention. In each instance, the trans-isomer of the namedproduct was obtained.

EXAMPLE 12,2-Dimethyl-5-[2-(3,4,5-trimethoxyphenyl)ethenyl]-3(2H)-furanone

To a mixture of 2,2,5-trimethyl-3(2H)-furanone (2.5 g, 19.8 mM) and3,4,5-trimethoxybenzaldehyde (4.7 g, 23.8 mM) in ethanol was added 1Naqueous sodium hydroxide (4 mL, 4mM). After the reaction mixture wasstirred for 48 hours at room temperature, the solution was concentratedto 50 mL and diluted with water (300 mL). The aqueous layer wasextracted with diethyl ether (4×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overmagnesium sulfate, filtered and concentrated under reduced pressure toafford a dark yellow crystalline solid. The crude product was purifiedby chromatography (silica gel, petroleum ether-ethyl acetate) to givelight yellow crystals (5.0 g, 83% yield), m.p. 149°-150° C.

Elemental analysis for C₁₇ H₂₀ O₅ : Calc'd: C, 67.09; H, 6.62. Found: C,66.98; H, 6.67.

81% inhibition at 25 mg/kg.

EXAMPLE 2 2,2-Dimethyl-5-[2-(4-fluorophenyl)ethenyl]-3(2H)-furanone

To a solution of 2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) and4-fluorobenzaldehyde (1.6 g, 13.2 mM) in ethanol (100 mL), was added 1Naqueous sodium hydroxide (1.6 mL, 1.6 mM). The reaction solution washeated at 50° C. for four hours. After the reaction solution was cooledto room temperature and diluted with saturated aqueous sodium chloride(200 mL) and water (200 mL), the aqueous solution was extracted withdiethyl ether (2×100 mL). The combined ethereal extracts were washedwith saturated aqueous sodium chloride (25 mL), dried over magnesiumsulfate, filtered and concentrated at reduced pressure to afford a darkyellow crystalline solid. The crude product was recrystallized fromhexane to give light yellow crystals (1.8 g, 45% yield), m.p. 55°-57° C.

Elemental analysis for C₁₄ H₁₃ O₂ F: Calc'd: C, 72.40; H, 5.64. Found:C, 72.05; H, 5.74.

ED₅₀ 11 mg/kg.

EXAMPLE 3 5-[2-(2,4-Difluorophenyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of dry diisopropylamine (3.3 mL, 24 mM) in drytetrahydrofuran (25 mL) at -78° C., was added dropwise 2.3N solution ofn-butyllithium in hexane (10.4 mL,24mM). After the reaction solution wasstirred 15 minutes, a solution of 2,2,5-trimethyl-3(2H)-furanone (2.0 g,16 mm) in tetrahydrofuran (10 mL) was added dropwise.Hexamethylphosphoramide (4.4 mL, 24 mM) was then added dropwise after 30minutes. Finally, 2,4-difluorobenzaldehyde (3.5 mL, 31.8 mM) intetrahydrofuran (10 mL) was added in one portion. The reaction solutionwas stirred 10 minutes when trifluoroacetic anhydride (11.87 g, 55.7 mM)was added in one portion. Again, the reaction solution was stirred 15,minutes when triethylamine (5.6 g, 55.7 mM) was added and was allowed towarm to room temperature. The reaction solution was partitioned betweensaturated aqueous sodium chloride (50 mL) and diethyl ether (50 mL). Thelayers were separated. The organic layers were then washed withsaturated aqueous sodium chloride (2×25 mL), dried over MgSO₄, filteredand concentrated under reduced pressure to give an orange liquid. Thecrude product was purified by chromatography (silica gel, pet.ether-ethyl acetate) to afford a yellow crystalline solid (2.6 g, 65%yield), m.p. 98.5°-100° C.

Elemental analysis for C₁₄ H₁₂ F₂ O₂ : Calc'd: C, 67.20; H, 4.83. Found:C, 66.99; H, 5.12.

52% inhibition at 25 mg/kg.

EXAMPLE 4 5-[2-(3,4-Difluorophenyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 3,4-difluorobenzaldehyde (1.9 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was heated at 50° C. for four hours. After the reactionsolution was cooled to room temperature, saturated aqueous sodiumchloride (400 mL) was added. The aqueous layer was extracted withdiethyl ether (3×100 mL). The combined ethereal extracts were washedwith saturated aqueous sodium chloride (50 mL), dried over MgSO₄,filtered and concentrated to give a yellow solid. The crude product wastriturated with 10% diethyl ether/pet. ether (50 mL) to give a paleyellow solid (1.66 g, 50% yield), m.p. 105°-106° C.

Elemental analysis for C₁₄ H₁₂ F₂ O₂ : Calc'd: C, 67.20; H, 4.83. Found:C, 67.08; H, 4.80.

47% inhibition at 25 mg/kg.

EXAMPLE 5 (E)-2,2-Dimethyl-5-[2-(4-bromophenyl)ethenyl]-3(2H)-furanone

To a solution of dry diisopropylamine (3.3 mL, 24 mM) in drytetrahydrofuran (25 mL) at -78° C., was added dropwise a 2.3N solutionof n-butyllithium in hexane (10.4 mL, 24 mM). After the reactionsolution was stirred for 15 minutes, a solution of2,2,5-trimethyl-3(2H)-furanone (2.0 g, 16 mM) in tetrahydrofuran (10 mL)was added dropwise. Hexamethylphosphoramide (4.4 mL, 24 mM) was thenadded dropwise for 30 minutes. Finally, p-bromobenzaldehyde (3.6 g, 19.2mM) in tetrahydrofuran (10 mL) was added in one portion. The reactionsolution was stirred 10 minutes when trifluoroacetic anhydride (5.6 mL,40 mM) was added in one portion. Again, the reaction solution wasstirred for 15 minutes when triethylamine (5.9 mL, 47.6 mM) was addedand was allowed to room temperature. The reaction mixture was thenpartitioned between saturated aqueous sodium chloride (50 mL) anddiethyl ether (50 mL). The layers were separated. The organic layerswere then washed with saturated aqueous sodium chloride (2×25 mL), driedover MgSO₄, filtered and concentrated under reduced pressure to givedark liquid. After the crude product was dissolved in dichloromethane(100 mL), trifluoroacetic anhydride (5.6 mL, 40 mM) was added. Afterthirty minutes, triethylamine (2.75 mL, 20 mM) was added. The resultingmixture was stirred for one hour, washed with 1N aqueous hydrochloricacid, dried over magnesium sulfate, filtered and concentrated underreduced pressure to afford an amber oil. The crude oil was purified bychromatography (silica gel, petroleum ether-ethyl acetate) to giveyellow-brown crystals (1.8 g, 39%). Recrystallization from hexane gavean analytically pure product, m.p. 109°-110° C.

Elemental analysis for C₁₄ H₁₃ BrO₂ : Calc'd: C, 57.36; H, 4.47. Found:C, 57.44; H, 4.50.

63% inhibition at 25 mg/kg.

EXAMPLE 6 2,2-Dimethyl-5-[2-(4-chlorophenyl)ethenyl]-3(2H)-furanone

To a solution of dry diisopropylamine (5.0 mL, 35.7 mM) in drytetrahydrofuran (150 mL) at -78° C., was added dropwise a 2.3 N solutionof nbutyllithium in hexane (15.5 mL, 35.7 mM). After the reactionsolution was stirred 15 minutes, a solution of2,2,5-trimethyl-3(2H)-furanone (3.0 g, 23.8 mM) in tetrahydrofuran (25mL) was added dropwise. Hexamethylphosphoramide (6.4 mL, 34.7 mM) wasadded dropwise after 30 minutes. Finally, p-chlorobenzaldehyde (3.0 g,2.7.8 mM) in tetrahydrofuran (25 mL) was added in one portion. Thereaction solution was stirred 15 minutes when trifluoroacetic anhydride(10.5 mL, 276 mM) was added in one portion. Again the reaction mixturewas stirred 15 minutes when triethylamine (5.9 mL, 48 mM) was added andthe mixture was allowed to warm to room temperature. The reactionmixture was then partitioned between saturated aqueous sodium chloride(50 mL) and diethyl ether (50 mL). The organic layer was separated andwashed with saturated aqueous sodium bicarbonate (2×25 mL) and saturatedaqueous sodium chloride (25 mL). The organic layer was dried overmagnesium sulfate, filtered and concentrated under reduced pressure togive an orange liquid which was purified by chromatography (silica gel,pet. ether-ethyl acetate) to afford yellow crystals (3.8 g, 65% yield),m.p. 91°-92° C.

Elemental analysis for C₁₄ H₁₃ ClO₂ : Calc'd: C, 67.61; H, 5.27. Found:C, 67.67; H, 5.56.

ED₅₀ 10.3 mg/kg.

EXAMPLE 75-[4-(4-Chlorophenyl)-1,3-butadienyl]-2,2-dimethyl-3(2H)-furanone

To a solution of p-chlorocinnamaldehyde (2.7 g, 16.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.45 g, 19.4 mM) in ethanol (100 mL),was added 1N aqueous sodium hydroxide (32 mL, 3.2 mM). The reactionsolution was stirred at room temperature for one day. After saturatedaqueous sodium chloride (400 mL) was added, the aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a brown solid. The crudeproduct was purified by chromatography (silica gel, pet. ether-ethylacetate) to afford yellow crystals (1.9 g, 36% yield), m.p. 95°-96° C.

Elemental analysis for C₁₆ H₁₅ ClO₂ : Calc'd: C, 69.95; H, 5.50. Found:C, 69.99 H, 5.57.

EXAMPLE 8 5-[2-(2,4-Dichlorophenyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 2,4-dichlorobenzaldehyde (2.3 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was heated at 60° C. for 4 hours. After the reaction solutionwas cooled, saturated aqueous sodium chloride (400 mL) was added. Theaqueous layer was extracted with diethyl ether (3×100 mL). The combinedethereal extracts were washed with saturated aqueous sodium chloride (50mL), dried over MgSO₄, filtered and concentrated to give a yellow solid.The crude product was triturated with 10% diethyl ether/pet. ether toafford a light yellow powder (2.6 g, 70% yield), m.p. 154°-156° C.

Elemental analysis for C₁₄ H₁₂ Cl₂ O₂ : Calc'd: C, 59.39; H, 4.27.Found: C, 59.26; H, 4.17.

EXAMPLE 9 5-[2-(3,4-Dichlorophenyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 3,4-dichlorobenzaldehyde (2.3 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was heated at 60° C. for 4 hours. After the reaction solutioncooled, saturated aqueous sodium chloride (400 mL) was added. Theaqueous layer was extracted with diethyl ether (3×100 mL). The combinedethereal extracts were washed with saturated aqueous sodium chloride (50mL), dried over MgSO₄, filtered and concentrated to give a yellow solid.The crude product was purified by chromatography (silica gel, pet.ether/ethyl acetate) to afford a light yellow solid (2.1 g, 56% yield),m.p. 100°-102° C.

Elemental analysis for C₁₄ H₁₂ Cl₂ O₂ : Calc'd: C, 59.39; H, 4.27.Found: C, 59.03; H, 4.14.

EXAMPLE 10 5-[2-(3,5-Dichlorophenyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 3,5-dichlorobenzaldehyde (2.3 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 gm, 15.9 mM) in ethanol (100 mL),was added 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was heated at 60° C. for 4 hours. After the reaction solutionwas cooled, saturated aqueous sodium chloride (400 mL) was added. Theaqueous layer was extracted with diethyl ether (3×100 mL). The combinedethereal extracts were washed with saturated aqueous sodium chloride (50mL), dried over MgSO₄, filtered and concentrated to give a yellow solid.The crude product was purified by chromatography (silica gel, pet.ether/ethyl acetate) to afford a light yellow solid (1.7 g, 45% yield),m.p. 129°-131° C.

Elemental analysis for C₁₄ H₁₂ Cl₂ O₂ : Calc'd: C, 59.39; H, 4.27.Found: C, 59.30; H, 3.9.

ED₅₀ 9 mg/kg.

EXAMPLE 112,2-Dimethyl-5-[2-[4-(trifluoromethyl)phenyl]ethenyl]-3(2H)-furanone

To a solution of dry diisopropylamine (5.0 mL, 35.7 mM) in drytetrahydrofuran (150 mL) at -78° C., was added dropwise a 2.3N solutionof n-butyllithium in hexane (15.5 mL, 35.7 MM). After the reactionsolution was stirred 15 minutes, a solution of2,2,5-trimethyl-3(2H)-furanone (3.0 g, 23.8 mM) in tetrahydrofuran (25mL) was added dropwise. Hexamethylphosphoramide (6.4 mL, 35.7 mM) wasthen added dropwise after 30 minutes. Finally,p-trifluoromethylbenzaldehyde (4.0 g, 28.5 mM) in tetrahydrofuran (25mL) was added in one portion. The reaction solution was stirred 15minutes when trifluoroacetic anhydride (10.5 mL, 76 mM) was added. Againthe reaction solution was stirred 15 minutes when triethylamine (5.9 mL,48 mM) was added and the mixture was allowed to warm to roomtemperature. The reaction mixture was partitioned between diethyl ether(50 mL) and saturated aqueous sodium chloride (100 mL). The organiclayer was separated and washed with saturated aqueous sodium bicarbonate(2×25 mL), and saturated aqueous sodium chloride (50 mL). The organiclayer was dried over magnesium sulfate, filtered and concentrated underreduced pressure to give an amber liquid. The crude product was purifiedby chromatography (silica gel, petroleum ether-ethyl acetate) to giveyellow crystals (3.2 g, 71% yield), m.p. 94°-95° C.

Elemental analysis for C₁₅ H₁₃ F₃ O₂ : Calc'd: C, 63.83; H, 4.64. Found:C, 63.83; H, 4.74.

30% inhibition at 25 mg/kg.

EXAMPLE 12(E)-2,2-Dimethyl-5-[2-[4-(methylthio)phenyl]ethenyl]-3(2H)-furanone

To a solution of dry diisopropylamine (5.0 mL, 35.7 mM) in drytetrahydrofuran (150 mL) at -78° C., was added dropwise a 2.3N solutionof n-butyllithium in hexane (15.5 mL, 35.7 mM). After the reactionsolution was stirred for 15 minutes, a solution of2,2,5-trimethyl-3(2H)-furanone (30 g, 23.8 mM) in tetrahydrofuran (25mL) was added dropwise. Hexamethylphosphoramide (6.4 mL, 34.7 mM) wasthen added dropwise after 30 minutes. Finally, p-methylthiobenzaldehyde(43 g, 28.5 mM) in tetrahydrofuran (25 mL) was added in one portion. Thereaction solution was stirred 15 minutes when trifluoroacetic anhydride(10.5 mL, 75 mM) was added in one portion. Again, the reaction solutionwas stirred 15 minutes when triethylamine (5.9 mL, 48 mM) was added andwas allowed to warm to room temperature. Then the reaction mixture waspartitioned between saturated aqueous sodium chloride (50 mL) anddiethyl ether (50 mL). The organic layer was separated and washed withsaturated aqueous sodium bicarbonate (2×25 mL) and saturated aqueoussodium chloride (25 mL). The organic layer was dried over magnesiumsulfate, filtered and concentrated under reduced pressure to give anamber liquid. The crude product was purified by chromatography (silicagel, pet. ether-ethyl acetate) to afford yellow crystals (3.0 g, 48%yield), m.p. 98°-99.5° C.

Elemental analysis for C₁₅ H₁₆ O₂ S: Calc'd: C, 69.20; H, 6.19. Found:C, 68.91; H, 6.35.

5% inhibition at 25 mg/kg.

EXAMPLE 132.2-Dimethyl-5-[2-[4-(methylsulfonyl)phenyl]ethenyl]-3(2H)-furanone

A solution of 2,2,5-trimethyl-3(2H)-furanone (1.5 g, 11.9 mM),4-methylthiobenzaldehyde (2.2 g, 14.3 mM) and 1N aqueous sodiumhydroxide (1.2 mL, 1.2 mM) in ethanol (30 mL) was stirred 16 hours atroom temperature. The reaction solution was diluted with saturatedaqueous sodium chloride (200 mL) and was extracted with diethyl ether(3×100 mL). The combined ethereal extracts were washed with saturatedaqueous sodium chloride (50 mL), dried over magnesium sulfate, filteredand concentrated under reduced pressure to give a yellow solid. Thecrude product was dissolved in dichloromethane (200 mL) thenm-chloroperbenzoic acid (6.15 g, 35.63 mM) was added and the reactionmixture was stirred 4 hours at room temperature. Then the mixture waswashed with 0.5M aqueous sodium sulfite (50 mL and saturated aqueoussodium bicarbonate (2×50 mL). The resulting solution was dried overMgSO₄, filtered and concentrated under reduced pressure to give a yellowsolid. The crude product was purified by column chromatography (silicagel, pet. ether-ethyl acetate) to afford pale yellow crystals (1.76 g,76% yield from ketone), m.p. 159°-160° C.

Elemental analysis for C₁₅ H₁₆ O₄ S: Calc'd: C, 61.62; H, 5.52. Found:C, 61.44; H, 5.48.

56% inhibition at 25 mg/kg.

ED₅₀ 10.6 mg/kg.

EXAMPLE 144-[2-(2,3-Dihydro-2,2-dimethyl-3-oxo-5-furanyl)ethenyl]benzonitrile

A solution of 2,2,5-trimethyl-3(2H)-furanone (1.5 g, 11.9 mM),4-cyanobenzaldehyde (1.7 g, 13.1 mM) and 1N aqueous sodium hydroxide(1.2 mL, 1.2 mM) in ethanol (50 mL) was stirred 24 hours at roomtemperature. The reaction mixture was diluted with saturated aqueoussodium chloride (200 mL) and extracted with diethyl ether (3×100 mL).The combined ethereal extracts were washed with saturated aqueous sodiumchloride (50 mL), dried over MgSO₄, filtered and concentrated underreduced pressure to give a yellow solid. The crude product was purifiedby column chromatography (silica gel, 9:1, hexane-ethyl acetate) toafford pale yellow crystals (1.5 g, 53% yield), m.p. 169.5°-170.5° C.

Elemental analysis for C₁₅ H₁₃ NO₂ : Calc'd: C, 75.30; H, 5.48; N, 4.85.Found: C, 75.23; H, 5.85; N, 5.86.

ED₅₀ 15 mg/kg.

EXAMPLE 153-[2-(2,3-Dihydro-2,2-dimethyl-3-oxo-5-furanyl)ethenyl]benzonitrile

A solution of 3-cyanobenzaldehyde (2.5 g, 19 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was stirred for one day at room temperature. After saturatedaqueous sodium chloride (400 mL) was added, the aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a yellow solid. The product wasrecrystallized from hexane-ethyl acetate to afford an analytically puresample (1.5 g, 43% yield), m.p. 155°-157° C.

Elemental analysis for C₁₅ H₁₃ NO₂ : Calc'd: C, 75.30; H, 5.48; N, 5.85.Found: C, 75.09; H, 5.25; N, 5.92.

EXAMPLE 162,2-Dimethyl-5-[2-(1-methyl-2-pyrrolyl)ethenyl]-3(2H)-furanone

To a solution of 1-methyl-2-pyrrolecarboxaldehyde (1.4 g, 12.7 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was heated at 70° C. for 48 hours. After the reaction solutionwas cooled to 0° C., saturated aqueous sodium chloride (400 mL) wasadded. The aqueous layer was extracted with ethyl acetate (3×100 mL).The combined ethyl acetate extracts were washed with saturated aqueoussodium chloride (50 mL), dried over MgSO₄, filtered and concentrated togive a brown solid. The crude product was purified by chromatography(silica gel, pet. ether-ethyl acetate) to give orange crystals (1.8 g,65% yield), m.p. 98.5°-100° C.

Elemental analysis for C₁₃ H₁₅ NO₂ : Calc'd: C, 71.87; H, 6.96; N, 6.45.Found: C, 71.83; H, 7.00; N, 6.37.

32% inhibition at 10mg/kg.

EXAMPLE 17 2,2-Dimethyl-5-[2-(2-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 2-pyridinecarboxaldehyde (1.1 g, 9.9 mM) and2,2,5-trimethyl-3(2H)-furanone (1.5 g, 11.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.2 mL, 1.2 mM). The reactionsolution was stirred at room temperature for 2 days. After saturatedaqueous sodium chloride (400 mL) was added, the aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a brown solid. The residue waspurified by chromatography (silica gel, pet. ether/ethyl acetate) toyield yellow crystals (1.6 g, 75% yield), m.p. 87.5°-89.0° C.

Elemental analysis for C₁₃ H₁₃ NO₂ : Calc'd: C, 72.56; H, 6.09; N, 6.51.Found: C, 72.62; H, 6.36; N, 6.59.

ED₅₀ 9 mg/kg.

EXAMPLE 18 2,2-Dimethyl-5-[2-(4-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of dry diisopropylamine (2.6 mL, 19.1 mM) in drytetrahydrofuran (350 mL) at -78° C., was added dropwise a 2.5M solutionof n-butyllithium in hexane (7.6 mL, 19.1 mM). After the reactionsolution was stirred for 15 minutes, a solution of2,2,5-trimethyl-3(2H)-furanone (20 g, 15.9 mM) in tetrahydrofuran (25mL) was added dropwise. Hexamethylphosphoramide (6.4 mL, 35.7 mM) wasthen added after 30 minutes. Finally, 4-pyridinecarboxaldehyde (2.5 g,23.5 mM) in tetrahydrofuran (25 mL) was added in one portion. Thereaction solution was stirred 15 minutes when trifluoroacetic anhydride(6.7 mL, 47.7 mM) was added in one portion. Again, the reaction solutionwas stirred 15 minutes before triethylamine (11 mL, 80 mM) was added andwas allowed to warm to room temperature. The reaction mixture wasconcentrated to 100 mL then diluted with diethyl ether (300 mL). Theorganic layer was extracted with 1N aqueous hydrochloric acid (100 mL).The acid layer was neutralized with solid sodium bicarbonate and washedwith diethyl ether (2×100 mL). The combined etheral layers were washedwith saturated aqueous sodium chloride (2×50 mL), dried over MgSO.sub.4, filtered and concentrated under reduced pressure to give a browncrystalline solid. The crude product was purified by chromatography(silica gel, pet. ether/ethyl acetate) to afford a yellow crystallinesolid (935 mg, 32% yield), m.p. 94°-96° C.

Elemental analysis for C₁₃ H₁₃ NO₂ : Calc'd: C, 72.54; H, 6.09; N, 6.51.Found: C, 72.21; H, 6.43; N, 6.89.

ED₅₀ 4 mg/kg.

EXAMPLE 19 2,2-Dimethyl-5-[2-(3-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 3-pyridinecarboxaldehyde (1.4 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was stirred at room temperature for one day. After saturatedaqueous sodium chloride (400 mL) was added, the aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a yellow solid. The crudeproduct was purified by chromatography (silica gel, hexane/ethylacetate) to afford a white crystalline solid (1.5 g, 53% yield), m.p.68°-70° C.

Elemental analysis for C₁₃ H₁₃ NO₂ : Calc'd: C, 72.54; H, 6.09; N, 6.51.Found: C, 72.73; H, 6.04; N, 6.50.

ED₅₀ 9.3 mg/kg.

EXAMPLE 20 5-[2-(4-Quinolinyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 4-quinolinecarboxaldehyde (2.8 g, 17.8 mM) and2,2,5-trimethyl-3(2H)-furanone (1.5 g, 11.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.2 mL, 1.2 mM). After the reactionsolution was stirred for 4 hours, saturated aqueous sodium chloride (400mL) was added. The aqueous layer was extracted with diethyl ether (3×100mL). The combined ethereal extracts were washed with saturated aqueoussodium chloride (50 mL), dried over MgSO₄, filtered and concentrated togive a brown oil. The crude product was purified by columnchromatography (silica gel, pet. ether-ethyl acetate) to yield a yellowcrystalline solid (1.2 g, 32% yield), m.p. 117°-118° C.

Elemental analysis for C₁₇ H₁₅ NO₂ : Calc'd: C, 76.96; H, 5.70; N, 5.28.Found: C, 76.99; H, 5.49; N, 5.25.

ED₅₀ 2.5 mg/kg.

EXAMPLE 21 2,2-Dimethyl-5-[2-(2-pyrazinyl)ethenyl]-3(2H)-furanone

To a solution of 2,2,5-trimethyl-3(2H)-furanone (2.1 g, 16.7 mM) andpyrazine carboxaldehyde (1.8 g, 16.7 mM) in ethanol (75 mL) was added1,8-diazbicyclo[5.4.0]undec-7-ene (DBU, 0.26 g, 1.7 mM). The resultingsolution was stirred overnight. Then the reaction solution was heated at60° C. for 4 hours. After the reaction solution was cooled to roomtemperature, it was diluted with saturated aqueous sodium chloride (200mL). The aqueous layer was extracted with dichloromethane (3×100 mL).The combined organic extracts were dried over sodium sulfate, filteredand concentrated under reduced pressure to afford a dark solid.Purification by column chromatography (silica gel, hexane-ethyl acetate)gave a pale yellow solid (1.6 g, 44% yield). Analytically pure productwas obtained by recrystallization from hexane, m.p. 120.5°-121.5° C.

Elemental analysis for C₁₂ H₁₂ N₂ O₂ : Calc'd: C, 66.65; H, 5.59; N,12.95. Found: C, 66.69; H, 5.68; N, 12.81.

56% inhibition at 10 mg/kg.

EXAMPLE 22 2,2-Dimethyl-5-[2-(3-thienyl)ethenyl]-3(2H)-furanone

To a solution of 3-thiophenecarboxaldehyde (1.5 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (1.5 g, 12 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.2 mL, 1.2 mM). the reactionsolution heated to 60° C. for 4 hours. After the reaction solutioncooled, saturated aqueous sodium chloride (400 mL) was added. Theaqueous layer was extracted with diethyl ether (3×100 mL). The combinedethereal extracts were washed with saturated aqueous sodium chloride (50mL), dried over MgSO₄, filtered and concentrated to give a yellowcrystalline solid. The residue was purified by chromatography (silicagel, hexane/ethyl acetate) to yield yellow crystals (2.1 g, 72% yield),m.p. 79°-80° C.

Elemental analysis for C₁₂ H₁₂ O₂ S; Calc'd: C, 65.43; H, 5.49. Found:C, 65.18; H, 5.62.

ED₅₀ 4 mg/kg.

EXAMPLE 23 2,2-Dimethyl-5-[2-(2-thienyl)ethenyl]-3(2H)-furanone

To a solution of 2-thiophenecarboxaldehyde (2.1 g, 19 mM) and2,2,5-trimethyl-3(2H)-furanone (2.0 g, 15.9 mM) in ethanol (100 mL), wasadded 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). The reactionsolution was stirred at room temperature for one day. After saturatedaqueous sodium chloride (400 mL) was added, the aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a yellow solid. The product wasrecrystallized from hexane to afford a yellow crystalline solid (1.5 g,43% yield), m.p. 75°-77° C.

Elemental analysis for C₁₂ H₁₂ O₂ S: Calc'd: C, 65.43; H, 5.49. Found:C, 65.42; H, 5.45.

1% inhibition at 10 mg/kg.

EXAMPLE 24 5-[2-(Benzo[b]thien-2-yl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 2-benzothiophenecarboxaldehyde (1.5 g, 9.2 mM) and2,2,5-trimethyl-3(2H)-furanone (1.6 g, 9.2 mm) in ethanol (100 mL), wasadded 1 N aqueous sodium hydroxide (1.2 mL, 1.2 mM). After the reactionsolution was stirred at room temperature for one day, saturated aqueoussodium chloride (400 mL) was added. The aqueous layer was extracted withdiethyl ether (3×100 mL). The combined ethereal extracts were washedwith saturated aqueous sodium chloride (50 mL), dried over MgSO₄,filtered and concentrated to give a brown solid. The residue waspurified by chromatography (silica gel, hexane-ethyl acetate) to afforda yellow solid (2.2 g, 58% yield), m.p. 103.5°-104° C.

Elemental analysis for C₁₆ H₁₄ O₂ S: Calc'd: C, 71.08; H, 5.22. Found:C, 71.06; H, 5.21.

17% inhibition at 10 mg/kg.

EXAMPLE 25 5-[2-(3-Furanyl)ethenyl]-2,2-dimethyl-3(2H)-furanone

To a solution of 3-furaldehyde (1.26 g, 13.2 mM) and2,2,5-trimethyl-3(2H)-furanone (1.5 g, 11.9 mM) in ethanol (50mL), wasadded 1N aqueous hydroxide (1.2 mL, 1.2 mM). After the reaction solutionwas stirred for one day at room temperature, saturated aqueous sodiumchloride (400 mL) was added. The aqueous layer was extracted withdiethyl ether (3×100 mL). The combined ethereal extracts were washedwith saturated aqueous sodium chloride (50 mL), dried over MgSO₄,filtered and concentrated to give a yellow solid. The crude product waspurified by chromatography (silica gel, hexane-ethyl acetate) to yieldyellow crystals (1.8 g, 74% yield), m.p. 79°-80° C.

Elemental analysis for C₁₂ H₁₂ O₃ : Calc'd: C, 70.57; H, 5.92. Found: C,70.37; H, 5.60.

35% inhibition at 10 mg/kg.

EXAMPLE 26 2-Phenyl-2-methyl-5[2-(3-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 3-pyridinecarboxaldehyde (1.03 g, 9.6 mM) and2,5-dimethyl-2-phenyl-3(2H)-furanone (1.0 g, 8 mM) in ethanol (50 mL),was added 1N aqueous sodium hydroxide (2.4 mL, 2.4 mM). The reactionsolution was heated at 60° C. for 8 hours. After the reaction solutioncooled to room temperature, saturated aqueous sodium chloride (200 mL)was added. The aqueous layer was extracted with diethyl ether (3×100mL). The combined ethereal extracts were washed with saturated aqueoussodium chloride (50 mL), dried over MgSO₄, filtered and concentrated togive a brown solid. The crude product was purified by chromatography(silica gel, pet. ether-ethyl acetate) to afford a yellow crystallinesolid (0.8 g, 36.3% yield), m.p. 106°-108° C.

Elemental analysis for C₁₈ H₁₅ NO₂ : Calc'd: C, 77.96: H, 5.45; N, 5.05.Found: C, 77.70; H, 5.15; N, 4.97.

ED₅₀ 5 mg/kg.

EXAMPLE 27 2-Methyl-2-phenyl-5-[2-(4-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 4-pyridinecarboxaldehyde (1.4 mL, 14.9 mM) and2,5-dimethyl-2-phenyl-3(2H)-furanone (2.0 g, 10.6 mm) in ethanol (50mL), was added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 323 mg, 2.1 mM).The reaction solution was heated at 60° C. for 4 hours. After thereaction solution cooled to room temperature, saturated aqueous sodiumchloride (400 mL) was added. The aqueous layer was extracted withdiethyl ether (3×100 mL). The combined dichloromethane extracts werewashed with saturated aqueous sodium chloride (50 mL), dried over MgSO₄,filtered and concentrated to give a red gummy product. The crude productwas purified by chromatography (silica gel, pet. ether-ethyl acetate) togive a white crystalline solid (1.1 g, 37% yield), m.p. 165°-166° C.

Elemental analysis for C₁₈ H₁₅ NO₂ : Calc'd: C, 77.96; H, 5.45; N, 5.05.Found: C, 77.73; H, 5.64; N, 5.05.

44% inhibition at 10 mg/kg.

EXAMPLE 28 2-Methyl-2-phenyl-5-[2-(2-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 2-pyridinecarboxaldehyde (1.2 mL, 1.2 mM) and2,5-dimethyl-2-phenyl-3(2H)-furanone (1.5 g, 8 mM) in ethanol (15 mL),was added 1,8-diazebicyclo[4.5.0]undec-7ene (DBU, 0.2 mL, 1.3 mM). Thereaction solution was heated at 80° C. for 5 hours. After the reactionsolution cooled to room temperature, saturated aqueous sodium chloride(400 mL) was added. The aqueous layer was extracted with dichloromethane(3×100 mL). The combined dichloromethane extracts were washed withsaturated aqueous sodium chloride (50 mL), dried over MgSO₄, filteredand concentrated to give a yellow solid. Purification by triturationwith 10% diethyl ether in hexane gave a pale pink solid (887 mg, 40%yield), m.p. 74.5°-76° C.

Elemental analysis for C₁₈ H₁₅ NO₂ : Calc'd: C, 77.96; H, 5.45; N, 5.05.Found: C, 77.66; H, 5.54; N, 5.11.

ED₅₀ 6 mg/kg.

EXAMPLE 29 4-[2-[2,3-Dihydro-2-phenyl-2-methyl-3-oxo-2-phenyl-5-furanyl]ethenyl]benzonitrile

To a solution of p-cyanobenzaldehyde (0.84 g, 6.4 mM) and2,5-dimethyl-2-phenyl-3(2H)-furanone (1.0 g, 5.3 mM) in ethanol (50 mL),was added 1N aqueous sodium hydroxide (0.5 mL, 0.5 mm). The reactionsolution was stirred at room temperature for two days. Then, saturatedaqueous sodium chloride (200 mL) was added. The aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a a beige solid. The crudeproduct was recrystallized from ethanol to afford a yellow solid (671mg, 42% yield), m.p. 187°-188° C.

Elemental analysis for C₂₀ H₁₅ NO₂ : Calc'd: C, 79.72; H, 5.00; N, 4.65.Found: C, 79.64; H, 5.28; N, 4.71.

4% inhibition at 10 mg/kg.

EXAMPLE 30 2-Methyl-2-phenyl-5-[2-(3-thienyl)ethenyl]-3(2H)-furanone

To a solution of 3-thiophenecarboxaldehyde (1.07 g, 9.6 mM) and2,5-dimethyl-2-phenyl-3(2H)-furanone (1.5 g, 8 mM) in ethanol (50 mL),was added 1N aqueous sodium hydroxide (1.6 mL, 1.6 mM). After thereaction solution was stirred at room temperature for one day, saturatedaqueous sodium chloride (400 mL) was added. The aqueous layer wasextracted with dichloromethane (3×100 mL). The combined dichloromethaneextracts were washed with saturated aqueous sodium chloride (50 mL),dried over MgSO₄, filtered and concentrated to give a yellow liquid. Theliquid was purified by chromatography (silica gel, pet. ether-ethylacetate) to afford a yellow solid (1.6 g, 71% yield), m.p. 75°-77° C.

Elemental analysis for C₁₇ H₁₄ O₂ S: Calc'd: C, 72.31; H, 5.00. Found:C, 72.29; H, 4.74.

EXAMPLE 314-[2-[2,3-Dihydro-2-(4-fluorophenyl)-2-methyl-3-oxo-5-furanyl]ethenyl]benzonitrile

To a solution of p-cyanobenzaldehyde (1.6 g, 11.8 mM) and2,5-dimethyl-2-(4-fluorphenyl)-3(2H)-furanone (2.0 g, 9.8 mM) in ethanol(75 mL), was added 1N aqueous sodium hydroxide (1.0 mL, 1 mM). After thereaction solution was stirred at room temperature for two days,saturated aqueous sodium chloride (400 mL) was added. The aqueous layerwas extracted with dichloromethane (3×100 mL). The combineddichloromethane extracts were washed with saturated aqueous sodiumchloride (50 mL), dried over MgSO₄, filtered and concentrated to give anorange liquid. The crude product was purified by chromatography (silicagel, pet. ether-ethyl acetate) to give a yellow crystalline solid (1.2g, 38% yield), m.p. 140°-142° C.

Elemental analysis for C₂₀ H₁₄ FNO₂ : Calc'd: C, 75.23; H, 4.42; N,4.39. Found: C, 75.24; H, 4.31; N, 4.35.

1% inhibition at 10 mg/kg.

EXAMPLE 322-Methyl-2-(4-fluorophenyl)-5-[2-(2-pyridinyl)ethenyl]-3(2H)-furanone

To a solution of 2-pyridinecarboxaldehyde (1.26 g, 10.2 mM) and2,5-dimethyl-2-(4-fluorophenyl)-3(2H)-furanone (2.0 g, 9.8 mM) inethanol (100 mL), was added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 0.2mL, 1.3 mM). The reaction solution was heated at 80° C. for 4 hours.After the reaction solution cooled to room temperature, saturatedaqueous sodium chloride (400 mL) was added. The aqueous layer wasextracted with diethyl ether (3×100 mL). The combined ethereal extractswere washed with saturated aqueous sodium chloride (50 mL), dried overMgSO₄, filtered and concentrated to give a yellow liquid. The crudeproduct was purified by chromatography (silica gel, pet. ether-ethylacetate) to yield a yellow solid (1.7 g, 59% yield), m.p. 70°-72° C.

Elemental analysis for C₁₈ H₁₄ FNO₂ : Calc'd: C, 73.22; H, 4.78; N,4.75. Found: C, 73.30; H, 4.61; N, 4.76.

92% inhibition at 10 mg/kg.

ED₅₀ 3.5 mg/kg.

EXAMPLE 332-(4-Fluorophenyl)-2-methyl-5-[2-(3-thienyl)ethenyl]-3(2H)-furanone

To a solution of 3-thiophenecarboxaldehyde (1.3 g, 1.2 mM) and2,5-dimethyl-2-(4-fluorophenyl)-3(2H)-furanone (2.0 g, 9.8 mM) inethanol (75 mL), was added 1N aqueous sodium hydroxide (2 mL, 2 mM). Thereaction solution was stirred at room temperature for one day. Aftersaturated aqueous sodium chloride (400 mL) was added, the aqueous layerwas extracted with dichloromethane (3×100 mL). The combineddichloromethane extracts were washed with saturated aqueous sodiumchloride (50 mL), dried over MgSO₄, filtered and concentrated to give abrown oil. The crude product was purified by chromatography (silica gel,pet. ether-ethyl acetate) to afford a yellow solid (1.8 g, 62% yield),m.p. 97°-98° C.

Elemental analysis for C₁₇ H₁₃ SFO₂ : Calc'd: C, 67.98; H, 4.36. Found:C, 68.23; H, 4.47.

22% inhibition at 10 mg/kg.

The cytoprotective and anti-ulcer activities of the compounds of thisinvention were established by demonstrating their ability to prevent theformation of gastric mucosal lesions produced by ethanol following theprocedure of Robert et al., Gastroenterology, 77 433 (1979), wherebymale Sprague-Dawley rats weighing 120-150 g were fasted for 24 hours (adlibitum water). The rats were placed in individual cages and deniedwater 2 hours or more before testing. At a fixed time beforeadministration of ethanol (usually 1 hour), the animals were orallyadministered either the test compound or itswater-carboxymethylcellulose vehicle. Ethanol was then administeredorally at a dose of 1 mL per animal. One hour after administration ofthe ethanol, the animals were sacrificed and their stomachs removed, cutalong the greater curvature and flushed clean with tap water.Macroscopic lesions on the gastric mucosa were graded from 0-3 basedupon the absence of lesions to the presence of lesions which approximate6 millimeters in length. Comparison of the treated group with thecontrol group permits expression of the results as percentage inhibitionof lesion formation as a direct measure of cytoprotection. The ED₅₀ iscalculated from a series of responses to different dosage levels of thecompound being tested and serves to establish the dose at which half theanimals did not develop lesions significantly different from the controlgroup. The results of these studies are given at the end of each exampleillustrating the preparation of the tested compound, supra, as thepercent inhibition or ED₅₀ where the latter value was determined.

Thus, the compounds of this invention may be administered neat or with apharmaceutical carrier to a patient in need thereof. The pharmaceuticalcarrier may be solid or liquid.

A solid carrier can include one or more substances which may also act asflavoring agents, lubricants solubilizers, suspending agents, fillers,glidants, compression aids, binders or tablet-disintegrating agents; itcan also be an encapsulating material. In powders, the carrier is afinely divided solid which is in admixture with the finely dividedactive ingredient. In tablets, the active ingredient is mixed with acarrier having the necessary compression properties in suitableproportions and compacted in the shape and size desired. The powders andtablets preferably contain up to 99% of the active ingredient. Suitablesolid carriers include, for example, calcium phosphate, magnesiumstearate, talc, sugars, lactose, dextrin, starch, gelatin, cellulose,methyl cellulose, sodium carboxymethyl cellulose, polyvinylpyrrolidine,low melting waxes and ion exchange resins.

Liquid carriers are used in preparing solutions, suspensions, emulsions,syrups, elixirs and pressurized compositions. The active ingredient canbe dissolved or suspended in a pharmaceutically acceptable liquidcarrier such as water, an organic solvent, a mixture of both orpharmaceutically acceptable oils or fats. The liquid carrier can containother suitable pharmaceutical additives such as solubilizers,emulsifiers, buffers, preservatives, sweeteners, flavoring agents,suspending agents, thickening agents, colors, viscosity regulators,stabilizers or osmo-regulators. Suitable examples of liquid carriers fororal and parenteral administration include water (partially containingadditives as above, e.g. cellulose derivatives, preferably sodiumcarboxymethyl cellulose solution), alcohols (including monohydricalcohols and polyhydric alcohols e.g. glycols) and their derivatives,and oils (e.g. fractionated coconut oil and arachis oil). For parenteraladministration, the carrier can also be an oily ester such as ethyloleate and isopropyl myristate. Sterile liquid carriers are used insterile liquid form compositions for parenteral administration. Theliquid carrier for pressurized compositions can be halogenatedhydrocarbon or other pharmaceutically acceptable propellent.

Liquid pharmaceutical compositions which are sterile solutions orsuspensions can be utilized by, for example, intramuscular,intraperitoneal or subcutaneous injection. Sterile solutions can also beadministered intravenously. The compound can also be administered orallyeither in liquid or solid composition form.

Preferably, the pharmaceutical composition is in unit dosage form, e.g.as tablets or capsules. In such form, the composition is sub-divided inunit dose containing appropriate quantities of the active ingredient;the unit dosage forms can be packaged compositions, for example,packeted powders, vials, ampoules, prefilled syringes or sachetscontaining liquids. The unit dosage form can be, for example, a capsuleor tablet itself, or it can be the appropriate number of any suchcompositions in package form.

The dosage to be used in the treatment of a specific gastric disordermust be subjectively determined by the attending physician. Thevariables involved include the specific disease state and the size, ageand response pattern of the patient. Based upon the activity profile andpotency of the compounds disclosed herein, an initial human dose withinthe range of about 1 to about 100 mg/day, by single or divided, oraladministration, should be appropriate. The containing dose may then bemodified to achieve the desired effect, within the range of about 0.5 toabout 50 mg/day, as personalized for the patient.

What is claimed is:
 1. A compound of the formula: ##STR6## in which R¹is alkyl of 1 to 6 carbon atoms, phenyl or halophenyl;R² is pyrazinyl;and n is 1 or
 2. 2. A compound of claim 1 in which R¹ is methyl, phenylor 4-fluorophenyl, n is 1 and R² is pyrazinyl.
 3. The compound of claim1 which is 2,2-dimethyl-5-[2-(2-pyrazinyl)ethenyl]-3(2H)-furanone.
 4. Apharmaceutical composition comprising a compound of the formula:##STR7## in which R¹ is alkyl of 1 to 6 carbon atoms, phenyl orhalophenyl;R² is pyrazinyl; and n is 1 or 2;and a pharmaceuticalacceptable carrier therefor.
 5. A pharmaceutical composition of claim 4in which R¹ is methyl, phenyl or 4-fluorophenyl, n is 1 and R² ispyrazinyl; and a pharmaceutical acceptable carrier therefor.
 6. A methodfor preventing gastric ulcers which comprises administering, orally orparenterally, to a mammal in need thereof a cytoprotective amount of acompound of the formula: ##STR8## in which R¹ is alkyl of 1 to 6 carbonatoms, phenyl or halophenyl;R² is pyrazinyl; and n is 1 or
 2. 7. Amethod for treating gastric ulcers which comprises administering, orallyor parenterally, to a mammal suffering from gastric ulcers an anti-ulceramount of a compound of the formula: ##STR9## in which R¹ is alkyl of 1to 6 carbon atoms, phenyl or halophenyl;R² is pyrazinyl; and n is 1 or2.